import { readFileSync } from "node:fs";

export function slugify(s) {
  return String(s)
    .toLowerCase()
    .normalize("NFKD")
    .replace(/[̀-ͯ]/g, "")
    .replace(/[^a-z0-9]+/g, "-")
    .replace(/^-+|-+$/g, "")
    .slice(0, 80);
}

export function titleCase(slug) {
  return String(slug)
    .split("-")
    .map((w) => w.charAt(0).toUpperCase() + w.slice(1))
    .join(" ");
}

export function todayInTz(tz) {
  const fmt = new Intl.DateTimeFormat("en-CA", {
    timeZone: tz,
    year: "numeric",
    month: "2-digit",
    day: "2-digit",
  });
  return fmt.format(new Date()); // en-CA => YYYY-MM-DD
}

/** ISO timestamp with Medellín's fixed -05:00 offset, e.g. 2026-06-28T14:37:09-05:00. */
export function isoInBogota(date = new Date()) {
  const parts = new Intl.DateTimeFormat("en-CA", {
    timeZone: "America/Bogota",
    year: "numeric",
    month: "2-digit",
    day: "2-digit",
    hour: "2-digit",
    minute: "2-digit",
    second: "2-digit",
    hourCycle: "h23",
  }).formatToParts(date);
  const g = (t) => parts.find((p) => p.type === t).value;
  return `${g("year")}-${g("month")}-${g("day")}T${g("hour")}:${g("minute")}:${g("second")}-05:00`;
}

/** A random Bogotá timestamp earlier today (between 00:00 and now) — varied but never future. */
export function randomTimestampTodaySoFar(tz = "America/Bogota") {
  const today = todayInTz(tz);
  const startMs = Date.parse(`${today}T00:00:00-05:00`);
  const nowMs = Date.now();
  const r = startMs + Math.floor(Math.random() * Math.max(1, nowMs - startMs));
  return isoInBogota(new Date(r));
}

export function addDays(isoDate, n) {
  const d = new Date(isoDate + "T00:00:00Z");
  d.setUTCDate(d.getUTCDate() + n);
  return d.toISOString().slice(0, 10);
}

export function loadJson(path) {
  return JSON.parse(readFileSync(path, "utf8"));
}

/** Extract the YAML frontmatter block (between the first two --- lines) as raw text. */
export function readFrontmatter(mdx) {
  const m = mdx.match(/^---\n([\s\S]*?)\n---/);
  return m ? m[1] : "";
}

/** Minimal frontmatter field readers (good enough for our controlled schema). */
export function fmString(fm, key) {
  const m = fm.match(new RegExp(`^${key}:\\s*"?([^"\\n]+?)"?\\s*$`, "m"));
  return m ? m[1].trim() : null;
}

export function fmArray(fm, key) {
  const m = fm.match(new RegExp(`^${key}:\\s*\\[([^\\]]*)\\]`, "m"));
  if (!m) return [];
  return m[1]
    .split(",")
    .map((s) => s.trim().replace(/^["']|["']$/g, ""))
    .filter(Boolean);
}